Celestial and Earthly Designs of Heart Valves
Dr. Hengchu Cao
Director of Engineering
The human heart is a very fascinating object. All hearts need four valves to function properly. The physiology function is to ensure blood circulating through the vasculature to deliver oxygen and vital nutrients to cells and organs in the body. The celestial design of the heart valve is achieved through the mighty force of evolution. Consequences of diseases disrupting normal cardiovascular function can be severe or fatal. When the natural valve fails, earthly man comes to the rescue in order to restore normal cardiovascular function through the use of implantable devices. Heart valves are basically check valves, meaning the flow is unidirectional. Malfunction can manifest in either inadequate opening, i.e. stenosis, or improper closing, i.e., regurgitation. More than half a century has passed since Starr and Edwards’ description of successful prosthetic valve replacement in 1961. Until recently, replacement of the heart valve is performed by a cardiothoracic surgeon in an open chest procedure where excorporal cardiopulmonary bypass is employed to temporarily support the circulation demand of the patient. There are many different types of prosthetic heart valves according to the construction material, design and delivery methods. Surgical heart valves refer to the conventional heart valve prostheses that are implanted by performing an open heart surgery, including mechanical valves, biological tissue valves, stentless xenograft and homograft. The emerging transcatheter heart valve replacement introduced within the last decade has transformed the landscape of future management of valvular diseased patients where valve replacement can be performed without open heart surgery. These heart valve prostheses are constructed with biological tissue for valve leaflet and a collapsible metal frame structure that can be crimped into a low profile and delivered through a catheter without open-heart surgery. This presentation will focus on the development of heart valves from the early experimental prototypes to the modern day practice where open heart operation is not needed. In particular, the development of biocompatible materials and innovation in the engineering design and evaluation will be discussed.
Dr. Cao is Director of Engineering at Edwards Lifesciences, leading the advanced materials and design technology group. Currently, his group is focused on the design and development of next-generation minimally invasive or transcatheter-delivered heart valve repair and replacement technology. Previously, he was involved in the research and development of ventricular assist devices to treat congestive heart disease. Dr. Cao holds a BS in Chemical Engineering from South China University of Technology, and a MS and Ph.D. in materials science from University of California at Berkeley. For the past few years, Dr. Cao has helped organizing a BEMA conference on Pre-clinical Device Evaluation, and was the co-chair for the 3rd ASME Frontiers in Biomedical Devices conference. More recently, as the past president for SABPA OC/LA chapter, he chaired the 4th and 5th Annual Biomedical Forum.